1. Field of the Invention
The present invention relates to an improved gas boiler, and more particularly to a gas boiler which has a simple internal pipeline structure, is easy to install, and can be manufactured at a low cost.
2. Description of the Prior Art
Gas boilers of a variety of types have been continuously proposed hitherto for producing hot water and room heating. FIG. 8 illustrates the internal structure of a conventional gas boiler 10 which generally includes a water tank 20, a circulation pump 30, a three way valve 40, a gas-heated heat exchanger 50, and a box accommodating a printed circuit board (hereinafter simply referred to as "PCB box") 70.
Conventional gas boiler 10 additionally includes a water valve 55, a supplementary water valve 57, a fan 60, a gas valve 74, a plurality of pipelines (not shown), and a plurality of electric wires (not shown).
Referring to FIG. 8, gas boiler 10 has a rear plate 12 consisting of steel. Rear plate 12 is joined with a front cover (not shown). Water tank 20 for retaining the heating water is placed on the upper left portion of rear plate 12. A water level sensing unit 80 is installed to the upper portion of water tank 20. Also, a bypass pipe 90 is installed at the upper right portion of water tank 20, which is connected to the upper left portion of heat exchanger 50 arranged to the right of water tank 20.
A heating water tank (not shown) and a combustion chamber 54 are equipped within heat exchanger 50. A gas supply pipe 72 is connected to the lower portion of heat exchanger 50, which supplies a gaseous fuel such as liquefied natural gas (hereinafter referred to as "LNG") or liquefied petroleum gas (hereinafter referred to "LPG") from an external gas source to heat exchanger 50. A gas valve 74 for adjusting the quantity of the LNG or LPG supplied to heat exchanger 50 is positioned in the middle of gas supply pipe 72. Fan 60 underlies heat exchanger 50.
Meanwhile, an overflow pipe 24, a heating water return pipe 26, a first heating water inlet pipe 28, and a supplementary water supply pipe 58 are connected to the bottom portion of water tank 20.
Here, heating water return pipe 26 is a flow path for the heating water returning from a heating place.
First heating water inlet pipe 28, for recirculating the heating water, extends from the lower portion of water tank 20 to be connected to circulation pump 30. Circulation pump 30 is driven by an electric motor (not shown) to raise the pressure of the heating water and circulate the heating water. A second heating water inlet pipe 32 is connected to the upper portion of circulation pump 30. Second heating water inlet pipe 32 extends from circulation pump 30 to be connected to the heating water tank of heat exchanger 50. A pump drain pipe 34 is connected to the lower portion of circulation pump 30. A drain cock 35 is installed at the center of pump drain pipe 34.
Supplementary water supply pipe 58 is connected to a water supply pipe 56. A supplementary water valve 57 is furnished at the middle of supplementary water supply pipe 58, which adjusts the quantity of the supplementary water supplied into water tank 20 via supplementary water supply pipe 58. Water supply pipe 56 provides fresh water and extends from the water source outside gas boiler 10 to enter into the heating water tank of heat exchanger 50. Water valve 55 is mounted in the middle of water supply pipe 56, which adjusts the quantity of the fresh water supplied via water supply pipe 56.
In the upper left portion of heat exchanger 50, water supply pipe 56 is connected to a hot water supply pipe 59, which extends from the left upper portion of heat exchanger 50 to the exterior of gas boiler 10 and supplies the hot water indirectly heated to have a raised temperature within heat exchanger 50 to a user.
Three-way valve 40 is disposed to the right of water supply pipe 56. Three-way valve 40 controls the flow of the heating water. An internal circulation pipe 42 and a heating water supply pipe 52 are connected to the upper portion of three-way valve 40. Internal circulation pipe 42 is connected to first heating water inlet pipe 28, which connects water tank 20 and circulation pump 30. Heating water supply pipe 52 extends from the heating water tank of heat exchanger 50 to be connected to three-way valve 40 via the bottom side of fan 60. A heating water discharge pipe 44, for discharging the heating water from heating water supply pipe 52 to the heating place, is connected to the lower portion of three-way valve 40. PCB box 70 is situated to the right of gas valve 74. The printed circuit board within PCB box 70 controls the operation of gas boiler 10.
The operation of conventional gas boiler 10 constructed as above will be briefly described in connection with the flow of the fluid.
The heating water which returns into gas boiler 10 after executing the room heating is introduced into water tank 20 via heating water return pipe 26. The heating water introduced into the interior of water tank 20 blends with the fresh water supplemented into water tank 20 via supplementary water supply pipe 58, and is provided to the interior of circulation pump 30 via first heating water inlet pipe 28.
The heating water introduced into circulation pump 30 is pressed by the pumping operation of circulation pump 30 to inflow into the heating water tank of heat exchanger 50 via second heating water inlet tube 32. The heating water admitted into the heating water tank is heated by a gas burner (not shown) disposed in combustion chamber 54 of heat exchanger 50. The heating water, whose temperature is raised by the heating, flows into three-way valve 40 via heating water supply pipe 52 extending from the right upper portion of the heating water tank.
At this time, if the operational mode of gas boiler 10 is the a heating mode, three-way valve 40 opens heating water discharge pipe 44 in accordance with a control signal from the printed circuit board to discharge the heating water. The heating water discharged as above is directed to the heating place via the heating water supply pipeline. The heating water which releases the heat returns to water tank 20 via heating water return pipe 26. The heating water admitted in water tank 20 is successively subjected to the above-stated circulation procedure.
In contrast to the above operation, when the operational mode of gas boiler 10 is the hot water mode, three-way valve 40 shuts off heating water discharge pipe 44 in accordance with the control signal from the printed circuit board. Therefore, the heating water having a raised temperature drifts within circulation pump 30 via internal circulation pipe 42. The heating water, which has a raised temperature and is introduced into circulation pump 30, is in turn provided to the heating water tank of heat exchanger 50 via second heating water inlet pipe 32 together with the heating water returning from the heating place by means of the pumping operation of circulation pump 40. The heating water admitted into the heating water tank is heated by the gas burner arranged within combustion chamber 54 as mentioned above. The heating water heated in this manner is introduced into three-way valve 40 via heating water supply pipe 52. Thereafter, the heating water is subjected to the aforestated circulation procedure to drift just within gas boiler 10.
On the other hand, apart from the circulation of the heating water, the fresh water is provided into the heating water tank of heat exchanger 50 via water supply pipe 56. The fresh water flows via water supply pipe 56, which is arranged as a coil within the heating water tank. At this time, the fresh water is changed into hot water of a high temperature by indirectly receiving the heat transmitted from the heating water which has been heated by the gas burner. The hot water prepared as above is guided to the user via hot water supply pipe 59 extending from water supply pipe 56 on the left of heat exchanger 50. Therefore, the hot water is constantly supplied while gas boiler 10 is operating.
However, in conventional gas boiler 10 as described above, there is a long and complicated pipeline for mutually connecting water tank 20, circulation pump 30, three-way valve 40, and heat exchanger 50. This intricate pipeline impedes the free arrangement of the components during the assembling of the gas boiler. Moreover, because that a copper pipe is adopted in consideration of corrosion and a hydraulic pressure in the pipeline of the gas boiler, the long pipeline is a factor in the high manufacturing cost of the conventional boiler. Furthermore, when a breakdown occurs and the gas boiler is repaired, the complicated pipeline requires considerable manpower and time for separating and replacing respective pipes.
U.S. Pat. No. 5,248,085, issued to Niels D. Jensen on the date of Sep. 28, 1993 may be given as one example of simplifying the internal construction of the gas boiler. Here, a switch mechanism placed between a first heat exchanger and a second heat exchanger is formed together with a control mechanism, a shaft, and a middle wall of a circulation pump housing to form one assembly unit, and thereby simplify the internal construction of the gas boiler. However, the Niels D. Jensen's gas boiler constitutes an assembly unit regardless of the position of a water tank, of the circulation and a three-way valve for contriving the simplification of the internal structure to thus fail in accomplishing an indeed simple structure of the complicated pipeline.